Phase Transition of [2,2]‐Paracyclophane – An End to an Apparently Endless Story |
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| Authors: | Dipl‐Chem Hilke Wolf Dr Dirk Leusser Dr Mads?R?V Jørgensen Dr Regine Herbst‐Irmer Dr Yu‐Sheng Chen Dr Ernst‐Wilhelm Scheidt Prof?Dr Wolfgang Scherer Prof?Dr Bo B Iversen Prof?Dr Dietmar Stalke |
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| Institution: | 1. Institut für Anorganische Chemie, Georg‐August‐Universit?t, Tammannstra?e 4, 37077 G?ttingen (Germany);2. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (USA);3. Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, 8000 Aarhus C (Denmark);4. University of Chicago, 9700 S. Cass. Avenue, Argonne, IL 60539 (USA);5. Institut für Physik, Universit?t Augsburg, Universit?tsstra?e 1, 86135 Augsburg (Germany) |
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| Abstract: | In this contribution, the solid‐state low‐temperature phase structure of 2,2]‐paracyclophane is unambiguously characterised by single‐crystal X‐ray analysis. Additionally, a heat capacity measurement was undertaken, which proves the existence of a λ‐type phase transition at 45 K, a transition that is connected with the formation of a secondary Cp/T feature at 60 K. The low‐temperature phase (<45 K) crystallises in the lower symmetry space group P$\bar 4$ n2, whereas the high‐temperature phase (>60 K) crystallises in space group P42/mnm. This proves what has been postulated both by experimental and theoretical chemists but has repeatedly been dismissed as speculation many times. |
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| Keywords: | paracyclophane phase transitions space group ambiguity structure elucidation thermal motion |
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